SHALGHOUDA/BENGHAZI, Libya, Aug 12 (Reuters) - Libyan rebels
said they had captured part of the oil town of Brega on Thursday
while their forces in the west pushed toward Zawiyah, trying to
get within striking distance of Muammar Gaddafi's capital.

Gaddafi is clinging to power despite a near five-month-old
NATO air campaign, tightening economic sanctions, and a
lengthening war with rebels trying to end his 41-year rule.

The rebels have seized large swathes of the North African
state, but are deeply divided and lack experience, and
Thursday's gains in the east broke weeks of stalemate.

One rebel spokesman said the opposition had captured the
residential districts of Brega but Gaddafi's forces still hold
western parts of the town where the oil facilities are located.

"It is liberated. It is under our control now," spokesman
Mossa Mahmoud al-Mograbi said of the eastern part of the town.

The residential area where the fighting was taking place is
about 15 km (9 miles) east of the oil terminal and sea port.

It was not immediately possible for a Reuters reporter to
verify the capture of Brega and rebels have repeatedly claimed
to have seized towns, only to be repelled by Gaddafi's forces.

In the western mountains, rebels said they reached the
village of Bir Shuaib, some 25 km (15 miles) from Zawiyah, which
has unsuccessfully risen up against Gaddafi twice this year.

It lies less than 50 km west of Tripoli, on the main road to
Tunisia, which has been a lifeline for Libya but has begun to
crack down on rampant smuggling of gasoline.

"We've gone past Nasr village and right now we're about 25
km from Zawiyah," said Faris, a rebel fighter. Rebels prevented
reporters from reaching the front to see for themselves.

Rebels in the western mountains do not operate as a single
force, as each town has its own command. But when they join
forces for major operations they can muster a few thousand men.

Their force is poorly trained and short of heavy weapons,
despite a French arms drop earlier this year, and most analysts
do not think they are capable of capturing Tripoli.

NATO HELP

In an effort to pile economic and military pressure on
Gaddafi, more countries are set to announce next week that they
will free frozen assets for the rebels, a British official said.

"While it's hard to predict when this will end, it's easy to
see the pressure is building on Gaddafi and it is only a matter
of time before he's forced to leave power," the official said.

Britain is playing a leading role in NATO air strikes
against Gaddafi's forces, which have weakened his armoury but
have not enabled the rebels to deliver a knockout blow.

Tightening the economic noose around Gaddafi, Tunisia said
on Thursday its troops were patrolling fuel stations to curb the
flow of smuggled gasoline into neighbouring Libya.

International sanctions and the effects of Libya's civil war
have disrupted normal supplies of fuel to parts of the country
under Gaddafi's control, but huge volumes of gasoline are
instead being smuggled across the Libyan-Tunisian border.

"The armed forces are now conducting checks at fuel stations
in the south of Tunisia ... so that neither Tunisians nor
Libyans can fill up with large quantities," Tunisian defence
ministry official Mokhtar Ben Nasr told a news conference.

"These checks are aimed at preventing the smuggling of
diesel and gasoline to Libya."

BREGA PROGRESS REPORT

The western battle is one of three widely separated rebel
fronts against Gaddafi forces. In the east around the ports of
Misrata and Brega, fighting had been bogged down in recent weeks
while the western rebels have advanced.

The two sides have been battling for months over Brega, 750
km east of Tripoli. The rebels see securing the oil facilities
as a tipping point in the war and hope to resume oil exports
from there as quickly as possible.

In the west, doctor Nuri Al-Fasi said one fighter had been
killed and four wounded on Thursday in the rebel push.

At a nearby field hospital, he looked over a rebel shot in
the stomach in the fighting in Nasr. "This is very serious. I
don't think he will make it," said al-Fasi, shaking his head.

Dozens of pick-up trucks packed with rebels drove to a
staging post a few kilometres behind the front line.

From rebel-held Misrata, east of Tripoli, rebels were
fighting to break a partial encirclement by Gaddafi forces,
striking south into the nearby village of Tawurgha.

Medical sources said six rebels were killed and 70 wounded
in their offensive on Tawurgha, from which Gaddafi's supporters
have been firing rockets at Misrata for weeks.

"Our rebels have just liberated Tawurgha. This is great news
... as this means that the rockets of Gaddafi's forces cannot
reach Misrata any more," said rebel spokesman Hassan Algallay.

Rebels said the offensive was led in coordination with NATO
to protect Misrata from missile attacks. He said NATO asked
rebels on Wednesday to paint their vehicles yellow and red.

The offensive comes days after Gaddafi's government accused
NATO of killing 85 civilians, including women and children, in
an air strike near Zlitan, west of rebel-held Misrata.

U.N. Secretary-General Ban Ki-Moon voiced alarm over recent
reports of civililan casualties and called on all sides to avoid
killing innocent people.

Dozens of Libyans protested outside the Hungarian embassy in
Tripoli, which has become an unofficial contact point for
European nations and the United States, against NATO airstrikes.

Rights group Amnesty International also called on NATO in a
statement to "thoroughly investigate" allegations of civilian
deaths in the strikes on the village of Majar, close to the
front line at Zlitan. NATO said it hit a military target.

(Additional reporting by Robert Birsel in Benghazi, Leon
Malherbe in Tripoli, Tarek Amara in Tunis, Souhail Karam in
Rabat, Joseph Nasr in Berlin and Mariam Karouny in Beirut;
Writing by Lin Noueihed, Editing by Tim Pearce)